Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 2-quart casserole dish.
Place zucchini in a pot fitted with a steamer basket over boiling water. Steam 5 minutes, or until tender but firm. Transfer to the casserole dish. Mix the dill, pepper, and margarine, and stir into the casserole dish, evenly coating zucchini. Layer tomato slices over zucchini, and sprinkle with basil and Romano cheese.
Bake 30 minutes in the preheated oven, until bubbly and golden brown.